Fuel selector positions in a Carbon Cub FX-3

[Neal]

First, I hope others will validate my understanding but I think people don't understand the fuel selector in a CubCrafters Carbon Cub FX-3. Some think OFF is where you should put the fuel selector when parked. My understanding, correct me if I'm wrong, but BOTH and OFF allow cross feeding of the tanks. So if you're parked on a hill with one wing down, you're going to move fuel between tanks in BOTH or OFF. I always park with my in LEFT.

 

[Cactus Charlie]

I set Left or Right on a slope and Off in the hangar. On a slope fuel will transfer when Off. Fuel may spill if slope is significant and/or tanks are close to full.

The use of Off in the hangar became a habit but I don't actually think it is needed. Someone was reporting that fuel leakage from the sniffle valve would be reduced or eliminated with fuel off. I don't think that's actually true.

Fuel leaks from the sniffle valve because the fuel system is still pressurized after engine stop and there will be a slow leakage of fuel past the servo idle cut off valve. How slow seems to be somewhat variable.